Intelligent multicolor nano-sensor based on nontoxic dual fluoroprobe and MOFs for colorful consecutive detection of Hg2+ and cysteine.

Ultrasensitive detection of Hg2+ in aquatic ecosystems is of great significance due to its high toxicity and ubiquity in water. Herein, using a one-step in-situ synthesis method, blue fluorescent carbon dots (CDs), red fluorescent InP/ZnS quantum dots (InPQDs), and MOFs (ZIF-8) integrated multicolor nano-sensor CDs/InPQDs@ZIF-8 was constructed for consecutive visual detection of Hg2+ and Cys. The InPQDs can act as the response unit for Hg2+ and Cys, with the limit of detection (LOD) of 8.68 and 37.96 nM, respectively. Significantly, the low detection limit combines with good specificity and accuracy of the nano-sensor meet the requirement for the safety monitoring and control of Hg2+ in drinking and environmental water. Moreover, the color recognition and processing software installed on smart phone can realize the real-time and rapid sensing of Hg2+ and Cys. A logic gate circuit was also devised, providing the possibilities for the application of the nano-sensor in the field of intelligent devices. As far as we know, this was the first example to apply InPQDs to the continuous multicolor visual detection of Hg2+ and Cys, which provided reference for the construction of environmentally-friendly dual emission fluorescent sensors for hazardous substance monitoring.